EP1049873B1 - Radial piston pump for producing high pressure fuel - Google Patents

Description

State of the art

The invention relates to a radial piston pump for High-pressure fuel generation in fuel injection systems of internal combustion engines, especially in a common rail injection system, with one stored in a pump housing Drive shaft which is eccentric or in Has circumferential direction cam-like elevations, and with preferably several radially in relation to the drive shaft a piston arranged in each cylinder space, at the ends facing the drive shaft each have a plate is attached, the piston by rotating the Radial drive shaft in the respective cylinder space Direction can be moved back and forth.

With such an internally supported radial piston pump are in from the rotating drive shaft onto the pistons Dependence on those sucked into the cylinder rooms Amounts of fuel applied relatively large forces to the Pressurize fuel. When sucking in Typically by a preloaded spring to the plate Drive shaft moved towards.

In the context of the present invention, it has been shown that the conventionally used plates and / or the pistons certain operating conditions, especially in a Element part filling, can be damaged. This Signs of wear can break the plate and / or the piston guide and are therefore undesirable.

The invention is therefore based on the problem of a Radial piston pump to provide the above overcomes disadvantages mentioned. In particular, fractions of the Plate and / or the piston can be prevented. The plate is supposed to work wear-free in operation, even at high ones To press. In doing so, the proper operation of the Radial piston pump even with partial filling of the Cylinder rooms can be guaranteed. The invention Radial piston pumps are designed to have a pump pressure of up to 2000 bar endure in the direction of conveyance and still inexpensive in the Manufacturing.

The problem is explained in the independent claim disclosed radial piston pump solved. Special Embodiments of the invention are in the subclaims disclosed.

The problem is with a radial piston pump High-pressure fuel generation in fuel injection systems of internal combustion engines, especially in a common rail injection system, with one stored in a pump housing Drive shaft which is eccentric or in Has circumferential direction cam-like elevations, and with preferably several radially in relation to the drive shaft a piston arranged in each cylinder space, at the ends facing the drive shaft each have a plate is attached, the piston by rotating the Radial drive shaft in the respective cylinder space Direction can be moved back and forth, solved in that the Plate is hinged to the associated piston. The in the frame the present invention found damage to the The plate and or the piston are subjected to bending stress of the piston. By articulating the plate the piston will be loaded by moments and moments Support forces reduced. Due to the movable attachment of the Plate on the piston prevents a moment from the Plate is transferred to the piston. So is also at Peak pressures up to 2000 bar ensure that the Radial piston pump according to the invention guaranteed, namely even with partial filling of the individual elements.

This is a special embodiment of the invention characterized in that the plate by a plate holder the piston is held. With such an inside supported radial piston pump has at the ends the piston attached plate makes contact with the drive shaft or with a ring with three mounted on the drive shaft flats offset by 120 °. The pistons are in operation the radial piston pump due to the eccentricity of the Drive shaft or through the cam-like elevations on the Drive shaft is reciprocated. there are in from the rotating drive shaft onto the pistons Dependence on those sucked into the cylinder rooms Amounts of fuel applied relatively large forces to the Pressurize fuel. It has shown, that the conventionally used plates, plate holders and / or pistons in certain operating conditions (Partial filling) extremely stressed and sometimes also to be damaged. This can lead to complete failure the pump come. The within the scope of the present invention detected damage to the plate, the plate holder and / or the piston are subjected to high bending stress of the plate holder and the piston by rotating the Drive shaft or the ring returned between the Drive shaft and the plate can be arranged if the Plate over coupling elements more or less rigid with the Piston is connected. By linking the plate to the Piston is loaded by the plate and the piston Moments and support forces reduced. This breaks the Plate, the plate holder and / or the piston prevented.

Another special embodiment of the invention is characterized in that the facing the drive shaft End of the piston has the shape of a spherical section and in a corresponding recess in the middle of the plate is recorded. The spherical formation of the piston foot and the result of the plate is that with appropriate design a more even surface pressure between the plate and the ring sitting on the eccentric shaft is reached. As a result, the one that occurs during operation of the radial piston pump Wear advantageously reduced.

Another special embodiment of the invention is characterized in that the plate has the shape of a round Has disc, whose peripheral edge is rounded and to Drive shaft tapers towards the shape of the plate holder is adapted to the rounded edge of the plate. This will when installed, a tilting of the plate relative to the Plate holder enables. This has the advantage that at a twisting (tilting) of the plate no moment on the Plate holder or the piston is transferred. This will reduces the load on the plate holder during operation.

Another special embodiment of the invention is characterized in that the plate on the to the piston facing side on the circumference has a chamfer. This will the assembly of the plate facilitated. When inserting the plate the chamfering of the edge of the plate ensures the plate holder that the plate holder is spread and slightly over the record goes.

Another special embodiment of the invention is characterized in that the piston has a collar, which merges into the spherical section-shaped end of the piston. The collar forms a stop for the plate holder on the Piston. This eliminates the need for snap rings that in conventional radial piston pumps for fastening the Plate holder to be used on the piston and partially due to breakage or loosening from the groove to failure of the pump - especially with partial filling.

Another special embodiment of the invention is characterized in that the piston comprises a plunger, its end facing the drive shaft as a spherical section is formed, which in a corresponding recess in the Middle of the plate is recorded. The spherical formation of the Piston foot and the plate has in addition to the mobility of the As a result, the surface pressure decreases. Thereby becomes the one occurring during the operation of the radial piston pump Wear advantageously reduced.

Another special embodiment of the invention is characterized in that on the piston between the plunger and a groove is provided in the ball section, in which a flanged edge engages, which is formed on the plate. Due to the flanged edge engaging in the groove, the Plate held on the piston. It is on one for the Mobility of the connection to ensure sufficient play. The geometric dimensioning of the connection is like this designed that a relatively low degree of freedom of the plate realized in the vertical direction of at least ± 10 degrees can be. The attachment of the plate to the invention Piston has the advantage that on a conventional Radial piston pumps used to attach the plate Plate holder can be dispensed with. That is, it will be fewer parts are required, which saves costs can.

Another special embodiment of the invention is characterized in that at least one in the flanged edge Opening is spared. The opening advantageously serves that the connection piston / plate lubricant supplied can be.

Another special embodiment of the invention is characterized in that the diameter of the Ball section slightly smaller than the diameter of the Piston. This dimensioning has proven to be in practice proven advantageous.

Another special embodiment of the invention is characterized in that the plate has the shape of a round Disc. Other basic shapes of the plate are also possible, but the round shape has proven to be advantageous proved.

Another special embodiment of the invention is characterized in that the plate on the to A chamfer on the side facing the drive shaft on the circumference having. The chamfer breaks the bottom edge of the plate and creates a softer transition. This will make the Stress on the plate reduced in the peripheral area.

Another special embodiment of the invention is characterized in that the plate has a collar. The federal government advantageously serves as a stop for a spring, which holds the plate against the drive shaft. there it is usually a coil spring that is arranged parallel to the piston and the suction stroke of the Piston causes.

Another special embodiment of the invention is characterized in that between the drive shaft and the Plate is arranged a ring. The ring is used for transmission of the forces from the eccentrically designed drive shaft the plate. The ring is advantageously sliding on the Drive shaft mounted. The ring can either be cylindrical or polygonal.

The present invention also relates to a method for Manufacture of a radial piston pump described above.

To attach the plate to the piston is conventional Radial piston pumps used a plate holder. This is done the plate holder is attached to the piston by a Snap ring. The plate is mounted on the piston complicated and time consuming.

Therefore, the present invention is further that Underlying problem is a method of making a pre provide radial piston pump that easy and can be executed quickly.

The problem is with a method of making one beforehand Radial piston pump described solved in that the Ball section of the piston in the recess of the plate is inserted until the ball section at the recess is present, and that the flange is then left on and at the same time with a molding tool against the spherical section and or the groove is deformed. Usually the plate initially hardened. The subsequent tempering then takes place inductive. The so-called "hot flanging" has the advantage that the flanged edge again due to the elasticity of the material springs back. This makes it flexible the connection required basic game automatically. The Process also has the advantage that it is largely can be automated.

The present invention generally has the advantage that Basic idea of the present invention in a simple manner and Be applied to existing radial piston pumps can. In general, the component strength, especially at Partial filling of the cylinder rooms, increased. The one on the housing intended center offset of a conventional Radial piston pump need not be changed.

Figur 1

zeigt einen Kolben und eine Platte von einer herkömmlichen Radialkolbenpumpe;

Figur 2

zeigt einen Kolben und eine Platte von einer Radialkolbenpumpe gemäß der vorliegenden Erfindung;

Figur 3

zeigt einen Kolben und eine Platte von einer herkömmlichen Radialkolbenpumpe;

Figur 4

zeigt einen Kolben und eine Platte von einer Radialkolbenpumpe gemäß der vorliegenden Erfindung im Schnitt;

Figur 5

zeigt eine Draufsicht der Platte aus Figur 4 vor der Montage an dem Kolben;

Figur 6

zeigt einen Schnitt durch die Platte aus Figur 5 entlang der Linie A-A; und

Figur 7

zeigt eine erfindungsgemäße Radialkolbenpumpe im Schnitt.

Further advantages, features and details of the invention emerge from the subclaims and the following description, in which exemplary embodiments are described in detail with reference to the drawings. The features mentioned in the claims and in the description can be essential to the invention individually or in any combination. Various ways of carrying out the claimed invention are explained in detail below with reference to the drawings.

Figure 1

shows a piston and a plate from a conventional radial piston pump;

Figure 2

shows a piston and a plate from a radial piston pump according to the present invention;

Figure 3

shows a piston and a plate from a conventional radial piston pump;

Figure 4

shows a piston and a plate of a radial piston pump according to the present invention in section;

Figure 5

shows a top view of the plate of Figure 4 before assembly on the piston;

Figure 6

shows a section through the plate of Figure 5 along the line AA; and

Figure 7

shows a radial piston pump according to the invention in section.

Figure 1 shows a section of a conventional Radial piston pump for high-pressure fuel generation Fuel injection systems for internal combustion engines. In figure 1 is only the part of the radial piston pump in section to which it is shown in the present invention arrives. The basic structure of a radial piston pump is assumed to be known and is therefore only in the following briefly mentioned.

The radial piston pump is used in particular in common rail injection systems for fuel generation from Internal combustion engines used. "Common rail" means as much as "common management", "common rail" or "common distribution bar". In contrast to conventional ones High pressure injection systems in which the fuel is over separate lines to the individual combustion chambers are promoted the injectors in common rail injection systems fed from a common line.

The radial piston pump shown in Figure 1 comprises an in a pump housing with a drive shaft eccentric shaft section. On the eccentric shaft section is a polygonal ring provided, against which the shaft section is rotatable. The Ring comprises several flats offset against each other a piston 1 is supported in each case. Instead of polygonal ring can also be a cylindrical ring be used. The pistons 1 are each in one Cylinder chamber 2 to and from the drive shaft in the radial direction movably added.

As shown in Figure 1, is on the drive shaft directed end of the piston 1 a plate 3 attached. The Plate 3 is through a plate holder 4, also called a cage is held on the associated piston 1. moreover is the plate 3 by a spring 5 against the (not shown) pressed ring. To prevent the Plate holder 4 slips off the piston 1 is a Snap ring 6 attached in a groove 7 of the piston 1.

In Figure 2 it is shown how a plate 13 according to the present invention is hinged to a piston 11. The Piston 11 has the shape of a hemisphere 17 at the end a flat 18 is provided. The flat 18 can also omitted. The plate 13 has a recess 19 in the middle, whose shape is adapted to the shape of the hemisphere 17. The Plate 13 is against the by a plate holder 14 Hemisphere 17 pressed.

Due to the spherical formation of the contact surface between the Piston 11 and the plate 13, it is possible that the Plate 13 relative to piston 11 tilts when a moment the plate 13 is applied. Tilting the plate 13 relative to the piston 11 is the special Formation of the plate edge and the plate holder 14 in favored favorably.

Apart from the recess 19, the plate 13 has the shape of a truncated cone that tapers away from the piston. The outer surface of the truncated cone is rounded. The Plate holder 14 is provided with a plurality of segments 20, the Shape is adapted to the outer surface of the plate 13. At the too the outer edge of the plate 13 facing the piston 11 is a Chamfer 21 provided which the assembly of the plate 13 the piston 11 relieved.

As a rule, the plate holder 14 is made of an elastic one Material made. If the plate 13 during assembly concentrically to the hemisphere 17 belonging to the piston 11 is moved, the segments 20 spread when they are in contact come to the chamfer 21. As a result of the tapering of the plate 13, the segments 20 go back together when the plate 13 with the recess 19 on the hemisphere 17 of the piston 11 is applied.

The plate holder 14 has a round opening 25 in the middle, through which the piston 11 projects in the installed state. The edge of the opening 25 of the plate holder 14 is in the Stop against a collar 25 which is formed on the piston 11 is. As a result, the plate holder is held on the piston 11. A snap ring 6 (see Figure 1), as in conventional Radial piston pumps are therefore not required. Finally, it is shown in FIG. 2 that the piston 11, the plate holder 14 and the plate 13 a common one Have axis of symmetry 23.

The only partially shown in Figures 1 and 2 Radial piston pump is used to remove fuel from a Pre-feed pump is delivered from a tank at high pressure too apply. The high pressure fuel will then in the common distribution strip mentioned above promoted.

FIG. 3 shows a section of a conventional one Radial piston pump for high-pressure fuel generation Fuel injection systems for internal combustion engines. In figure 3 is only the part of the radial piston pump in section to which it is shown in the present invention arrives. The basic structure of a radial piston pump is shown in Figure 7.

In Figure 3, a piston 1 is shown in a Cylinder chamber 2 can be moved back and forth. At the free end the piston 1, a plate 3 is attached. The plate 3 is through a plate holder 4, which can also be used as a cage or Is called spring plate, held on the piston 1. moreover is the plate 3 by a spring 5 with a compressive force applied. To prevent the plate holder 4 from the piston 1 slides down, a snap ring 6 in one Groove 7 of the piston 1 attached.

In the operation of the radial piston pump it happens that the Plate 3 relative to piston 1 in plate holder 4 twisted. Twisting the plate can damage it and to breakage of the plate, the piston and / or the plate holder to lead. This with conventional radial piston pumps problem arising is solved by the present invention solved.

In Figure 4 it is shown how a plate 13 according to the present invention to a plunger 11 with a total 10 designated piston is articulated. The plunger 11 has End in the form of a sphere 17. The plate 13 has in the middle a recess 19 which serves as a socket. Through the spherical formation of the contact surface between the plunger 11 and the plate 13, it is possible that the plate 13 twisted relative to the plunger 11 when a moment on the Plate 13 is applied.

The plate 13 is on the side facing away from the piston 10 provided with a chamfer 20a. The chamfer 20a goes in a federal government over 22. The collar 22 forms a stop for one Spring 23a.

The recess 19 is bordered by a flange 24. in the assembled state, the flange 24 engages in a Groove 25a between the plunger 11 and the ball 17 on the Piston 10 is formed. It is between the flange edge 24 and the ball 17 or the groove 25a enough play present that the plate 13 relative to the piston 10th can move.

In Figures 5 and 6, the plate 13 is on before assembly shown the piston. In Figure 6 it can be seen that the Flanged edge 24 of the plate 13 parallel to the center line 26a the plate 13 runs. In comparison, the flanged edge 24 slightly bent inwards in FIG. 4. In the in FIG. 6 shown state, the ball 17 during assembly in System with the surface of the recess 19 are brought. The flanged edge 24 can then be started inductively and using an appropriate tool against the piston be pressed. After the start, the flanged edge turns up 24 due to the elasticity of the material used by even so far back until the aforementioned game between the flanged edge 24 and the ball 17 is reached. Then located the flanged edge 24 slightly follows in that shown in FIG inside bent state, in which the plate 13 articulated with the Piston 10 is connected.

As best shown in Figure 5, are in the crimp edge 24 two openings 28, 29 are provided for lubricating the Serve connection between the piston 10 and the plate 13.

In Figure 7 is a complete radial piston pump according to the presented present invention. The radial piston pump is especially in common rail injection systems Fuel generation used by diesel engines. there "common rail" means "common line", "common rail" or "common rail". in the Contrary to conventional high pressure injection systems, in which the fuel via separate lines to the individual Combustion chambers is promoted, the injectors are in Common rail injection systems from a common line fed.

The radial piston pump shown in FIG. 7 comprises an in a pump housing 50 mounted drive shaft with a eccentrically formed shaft section 51. On the eccentric shaft portion 51 is a polygonal ring 52 provided, against which the shaft section 51 is rotatable is. The ring 52 comprises three mutually offset flats 54 against which a piston 55 is supported. Instead of polygonal ring 52 can also be a cylindrical ring be used. The pistons 55 are each in one Cylinder chamber 56 towards the drive shaft in the radial direction and movably added. There is one on each of the pistons 55 Plate 58 articulated. The connection between the piston 55 and plate 58 is shown enlarged in FIG is described above.

The radial piston pump shown in FIG. 7 serves to Fuel coming from a pre-feed pump from a tank is supplied to be subjected to high pressure. The one with High pressure fuel is then turned into a promoted common rail.

Claims (14)

1. Radial piston pump for generating high fuel pressures in fuel injection systems of internal combustion engines, especially in a common-rail injection system, having a drive shaft (51) of eccentric design supported in a pump housing (50), and preferably having a plurality of pistons (1, 10, 55) arranged radially in relation to the drive shaft (51) in a respective cylinder chamber (2, 56), a plate (3, 13, 58) being fitted at the ends of each of the pistons facing the drive shaft (51), the pistons (1, 10, 55) being made to reciprocate in a radial direction by rotation of the drive shaft (51) in the respective cylinder chamber (2, 56) and a ring (52) with flattenings (54) being arranged between the drive shaft and the plate (13, 58), characterized in that the plate (13, 58) is pivoted to the associated piston (10, 55).
2. Radial piston pump according to Claim 1, characterized in that the plate (3, 13) is held to the piston (11) by a plate holder (4, 14).
3. Radial piston pump according to Claim 2, characterized in that the end of the piston (11) facing the drive shaft takes the form of a spherical segment (17) and is received into a corresponding depression (19) in the middle of the plate (13).
4. Radial piston pump according to either of Claims 2 or 3, characterized in that the plate (13) takes the form of a circular disk, the circumferential edge of which is rounded and tapers towards the drive shaft, the shape of the plate holder (14) being matched to the rounded edge of the plate (13).
5. Radial piston pump according to one of Claims 2 to 4, characterized in that the plate (13) has a peripheral bevel (21) on that side facing the piston (11).
6. Radial piston pump according to one of Claims 2 to 5, characterized in that the piston (11) has a flange (26), which merges into the spherical segmental end (17) of the piston (11).
7. Radial piston pump according to Claim 1, characterized in that the piston (10, 55) comprises a tappet (11), of which the end facing the drive shaft is designed as spherical sagment (17), which is received into a corresponding depression (19) in the middle of the plate (13, 58).
8. Radial piston pump according to Claim 7, characterized in that a groove (25a), in which a flanged edge (24), formed on the plate (13, 58), engages, is provided on the piston (10, 55) between the tappet (11) and the spherical segment (17).
9. Radial piston pump according to Claim 8, characterized in that at least one port (28, 29) is recessed in the flanged edge (24).
10. Radial piston pump according to one of Claims 7 to 9, characterized in that the diameter of the spherical segment (17) is slightly less than the diameter of the piston (10, 55).
11. Radial piston pump according to one of Claims 7 to 10, characterized in that the plate (13, 58) takes the form of a circular disk.
12. Radial piston pump according to one of Claims 7 to 11, characterized in that the plate (13, 58) has a peripheral bevel (20a) on that side facing the piston.
13. Radial piston pump according to one of Claims 7 to 12, characterized in that the plate (13, 58) has a flange (22).
14. Method for the manufacture of a radial piston pump according to one of Claims 8 to 13, characterized in that the spherical segment (17) of the piston (10, 55) is introduced into the depression (19) in the plate (13, 58) until the spherical segment (17) bears against the depression (19), and that the flanged edge (24) is then tempered and simultaneously deformed by a forming tool against the spherical segment (17) and/or the groove (25a).

Images